Inflatable balloon printing devices are well known for applying colour drawings or letterings on the external balloon surface, usually for advertisement purposes. A known method of applying colour on a balloon is a silk screen process, in which the balloon is inflated, and biased against an ink permeable silk screen until the balloon is yieldingly deformed against the screen so as to obtain a temporarily flat balloon surface in contact with the silk screen. Colour is then applied on this flat balloon surface through the silk screen, with a wiper that horizontally runs along the screen. The balloon is then removed from the silk screen, and retrieves its original shape, with the desired design now inprinted on the balloon surface. Several colours can be applied in this fashion by moving the balloon through sequential colour printing stations. For example, on a light-coloured balloon such as a white balloon, four colouring stations could be used, one station for black colour printing, and three stations for printing the three primary colours, i.e. red, yellow and blue.
Balloon printing apparatuses have been devised over the years which include a number of sequential stations, namely a station for installing the balloon on the apparatus, an inflating station for inflating the balloon, several colour printing stations for applying the colour on the balloon surface, a drying station for speeding up the ink colour drying of the balloon, and a removal station for removing the balloon from the apparatus, and possibly simultaneously removing the air from the inflated balloon.
An important problem associated with the conventional apparatuses as described above is that they may allow, in their sequential colour printing stations, the different colours to become slightly offset relative to one another, thus blurring the image on the balloon. Indeed, a slight accidental displacement of the balloon, due to air currents or the acceleration and deceleration sudden stepwise movements of the balloon from one station to the other, may cause a difference in the position of the balloon during printing relative to its desired position, resulting in the colour being printed thereon at an offset position. The image printed on the balloon may consequently be undesirably blurred and unclear due to poor colour registration, which is called the shadow effect.
Means for stabilizing the balloon have been devised, such as in U.S. Pat. No. 4,478,142 issued in 1984 to C. Santorineos. In this patent, a balloon carrying member comprising a ring holds the balloon around its neck portion while it is moved from one station to another. However, tilting motion of the balloon is not prevented with this device, and the balloon may still move relative to its ring member from one station to another. The Santorineos patent also shows a vertically movable cup-like cradle which underlies and supports the balloon during the printing operations. However, this cradle does not follow the balloon from one station to another, and thus the balloon remains unsupported between stations, while a cradle engages the balloon at each printing station. The balloon is thus prone to move relative to its ring member from one station to another and to be pushed by the next cradle in an incorrect position against the next silk screen.